1. Field of the Invention
The present invention relates to an interior illumination lamp, for example, attachable to the inside of an automobile.
2. Related Art
Conventionally, there is provided an interior illumination lamp installed in the inside of an automobile as shown in FIG. 9, for example, Unexamined Japanese Patent Publication 2003-335191.
As shown in FIG. 9, this room illuminating light 100 has a function-concentrated unit 101 which is a functional part fitted in an aperture provided in the ceiling of the automobile, and a cover 102 of rectangle shape which is made of a synthetic resin and constitutes a design part capable of fitting in the interior material of the ceiling as a configuration integrated with this function-concentrated unit 101. The cover 102 has surrounding walls 102a to be fitted in the frame or inner panel of the automobile body, a flange 102b located in the indoor side adjacent to this surrounding walls 102a, and a light-transmitting lamp cover 102c in the inside of this flange 102b. And, at one end of the lamp cover 102c, a pushing type operating button 102d that operates to turn on or off a switch 101a to be described later on is arranged in a freely mobile manner in the vertical direction.
On the other hand, function-concentrated unit 101, which is to be electrically connected to a wire harness (W/H) arranged in the rear side of the interior material for the ceiling via a pressure contact connector 101b, comprises a switch 101a operating a bulb 103 on and off, a light-emitting bulb 103, and a reflecting board 104 that directs the light emitted from the bulb 103 towards the inside of the automobile through the lamp cover 102c. 
Thus, the function-concentrated unit 101 is integrated with the cover by being electrically connected to a wire harness W/H arranged at the rear side of the interior material by means of a pressure contact connector 101b and fitted in the inside of the surrounding walls 102a. Since, in this integrated structure, an operating button 102d provided in the cover 102 is positioned right above (interior side) the push button 101c of the switch 101a in the function-concentrated unit 101, the switch 101a can be switched by pushing operating button 102d. 
Meanwhile, in the function-concentrated unit 101 of the aforementioned room illuminating light 100, the switch 101a is configured integrally with another function-concentrated unit 101, i.e., the pressure contact connector 101b and reflection board 104. For that reason, in the case where a switch of a different shape (for example, push-lock type, sliding switching type, alternate-lock type, etc.) is adopted or exchanged, the entire function-concentrated unit 101 had to be newly produced in conformity with the shape of the switch and install the switch therein, which was not only troublesome, but also unfavorably uneconomical.